Cathode ray tube with plural beams for each color element

ABSTRACT

A color picture or cathode ray tube is provided with a singlegun generating a plurality of groups of electron beams which are all focused on the color phosphor screen by a common electron lens with all of the beams preferably passing through the optical center of such lens, and the beams of each group are made to have a common landing spot on the screen so as to simultaneously excite respective color phosphors of the screen and thereby provide a color picture of enhanced brightness.

United States Patent 51 3,696,26 1 Miyaoka [451 Oct. 3, 1972 [54] CATHODE RAY TUBE WITH PLURAL 2,735,031 2/ 1956 Woodbridge ..3l3/70 C BEAMS FOR EACH COLOR ELENIENT 3,065,295 11/1962 Glenn ..3l3/70 C X Inventor: Snri y Fuj Sawa ju YOShlda et l C taku, 13 Fujigaoka l, Kanagawaken, Fujisawa-shi, Japan Pnmary Examlfwr Rb ert Segal Attorney-Lew1s H. Eslmger, Alvin Smderbrand and Flledi g- 1970 Curtis, Morris & Safford [21] Appl. No.: 66,283

[57] ABSTRACT 30 Foreign Application Priority Data color picture or cathode ray tube is provided with a single-gun generating a plurality of groups of electron Aug. 23, 1969 Japan ..44/66582 beams which are n focused on the color phosphor screen by a common electron lens with all of the [52] US. Cl. ..313/69 C, 313/70 C, 313/77 beams preferably passing through the Optical Center of [51] l 31/20 H011 29/80 H013 29/56 such lens, and the beams of each group are made to [58] Field of earch .3l3/69 C, 70 C, 92 B have a common landing Spot on the Screen so as to simultaneously excite respective color phosphors of [56] References cued the screen and thereby provide a color picture of UNITED STATES PATENTS enhanced brightness.

2,721,287 10/1955 Van Ormer ..3l3/69 C 8 Claims, 9 Drawing Figures fi/RMIR) KZRM'ZR) 5 (2 B skfek) G5 8 B G 56 G1 aid/M26) Lm L5 63 5R V KR r S6 0-- l KG l $5 v M 56 1- 915 PB l I 55(519) fl/GMIG) 2.5?1257 2 l0 PAIENTEDnma 1912 3,696,261

sum 2 or 3 a l 58 (BR) 56) I INVEXTOR SENRI MIYAOKA BY I .5/

CATHODE RAY TUBE WITH PLURAL BEAMS FOR EACH COLOR ELEMENT This invention relates generally to color picture or cathode ray tubes of the single-gun, plural-beam type, and particularly to tubes of that type in which the plural beams are passed through the optical center of a common electron lens by which the beams are focused on the color phosphor screen.

In single-gun, plural beam color picture tubes of the described type, for example, as specifically disclosed in US. Pat. No. 3,448,316, issued June 3, 1969, and having a common assignee herewith, three laterally spaced electron beams are emitted by a beam generating or cathode assembly and directed in a common substantially horizontal plane with the-central beam coinciding with the optical axis of the single electron focusing lens and the two outer or side beams being converged to cross the central beam at the optical center of the lens and thus emerge from the latter along paths that are divergent from the optical axis. Arranged along such divergent paths are pairs of convergence deflecting plates having voltages applied thereacross to laterally deflect the divergent side beams in a substantially horizontal plane for causing all beams to converge at a point on the apertured beam selecting grid or shadow mask associated with the color screen. After passing through an aperture of the grid or mask, the outer or side beams again diverge from the central beam and the three beams impinge on respective color phosphors arranged in arrays or sets forming repetitive patterns on the color screen.

In the above described color picture tube, a single electron beam is provided for exciting the color phosphors of each color. Thus, for example, the central beam may excite the green phosphors, while the outer or side beams excite the red and blue phosphors, respectively. With such arrangement, the brightness of the picture formed on the screen is dependent on the beam current in each of the three electron beams impinging on the respective color phosphors. If an attempt is made to increase the brightness of the color picture by increasing the beam current or current density in each electron beam, there is a resulting increase in the diameter of each electron beam at a cross-over point thereof, and the consequent increase in the diameter of the beam spot formed by each beam on the screen causes deterioration of the resolution of the picture.

Accordingly, it is an object of this invention to provide a color picture tube of the single-gun, plural-beam type which produces a bright picture of high resolution.

Another object is to provide a color picture tube of the single-gun, plural-beam type in which the brightness of the picture is increased without undesirably increasing the beam current density, and hence without deterioration of the picture resolution.

In accordance with an aspect of this invention, an extremely bright picture is achieved with a single-gun, plural beam color picture tube in which the single gun generates a plurality of groups of electron beams, and in which the beams of each group have a common landing spot on the screen so as to simultaneously excite respective color phosphors of the screen.

More particularly, in an embodiment of this invention, three laterally spaced apart groups of vertically spaced electron beams are emitted by a beam generating assembly. The beams of the central group lie in a vertical plane containing the optical axis of a single main electron focusing lens by which all of the beams are focused on the screen, and the beams in such vertical plane are converged, as by an auxiliary electron lens, so as to cross each other substantially at the optical center of the main lens. The beams of the outer or side groups lie in respective vertical planes which are laterally converged, as by the auxiliary electron lens, to intersect substantially at the optical center of the main lens, and the beams of each side group are converged in the respective vertical plane, once again by the auxiliary lens, so as to cross each other substantially at the mentioned optical center. Thus, all of the beams pass through the center of the main electron lens for focusing thereby on the screen without significant coma or spherical aberration. Beams of the central and side groups emerge from the main electron lens along vertically divergent paths lying in respective vertical planes, and the planes containing the emergent beams of the side groups diverge laterally from the plane containing the emergent beams of the central group. Arranged between themain electron lens and the apertured beam selecting grid are vertical and horizontal convergance deflecting devices which respectively operate to vertically converge the beams of each group to a common landing spot on the color screen and to horizontally converge the beams of the side groups with the beams of the central group at a common vertical line on the beams selecting grid.

The above, and other objects, features and advantages of this invention will be apparent in the following detailed description of illustrative embodiments thereof which is to be read in connection with the accompanying drawings, wherein:

FIG. 1 is a schematic, horizontal sectional view through the axis of a color picture tube according to an embodiment of this invention;

FIG. 2 is a transverse sectional view taken along the line 2-2 on FIG. 1;

FIG. 3 is a sectional view similar to that of FIG. 1, but taken in a vertical plane including the tube axis;

FIGS. 4 and 5 are diagrammatic views illustrating the optical equivalent or analogy of the tube according to this invention as shown by FIGS. 1 and 3, respectively;

FIGS. 6 and 7 are views similar to FIGS. 1 and 3, respectively, but showing another embodiment of this invention;

FIG. 8 is a sectional view taken on the line 88 on FIG. 6; and

FIG. 9 is an end view of a magnetic deflection device that may be employed for horizontally converging the beams in the tubes according to this invention.

Referring to the drawings in detail, and initially to FIG. 1 thereof, it will be seen that a single-gun, pluralbeam color picture tube 10 in accordance with this invention is then shown to comprise a glass envelope 11 (indicated in broken lines) having a neck 12 and cone 13 extending from the neck to a face plate carrying a color screen S made up of the usual arrays or sets of color phosphors S 5 and S and with an apertured beam selecting grid or grill A disposed in back of the screen and spaced a small distance therefrom. Disposed within neck 12 is an electron gun A having cathodes K K and K which constitute beamgenerating sources having the respective beamgenerating surfaces disposed as shown in a plane which is substantially perpendicular to the axis of the electron gun A. In the embodiment shown, the beam generating surfaces of cathodes K K and K are vertically elongated and the cathode K is centered on axis of the gun while the cathodes K and K are spaced laterally or horizontally from cathode K at opposite sides of the latter.

A first grid G is spaced axially from the beamgenerating surfaces of cathodes K K and K and has paired apertures h and h,,;, h and/1' and h and 11' formed therein. The apertures of each pair are vertically spaced apart so as to be symmetrically disposed above and below a horizontal plane containing the axis of gun A. Further, the pairs of apertures h and h' h,,,- and h and h and 11' are laterally spaced apart so as to be in alignment axially with the beam generating surfaces of cathodes K K and K respectively (FIG. 2).

A common grid G is spaced from the first grid G and has paired apertures h and h' h and h and I1 and 11' formed therein in alignment with the similarly numbered apertures of the first grid G Successively arranged in the axial direction away from the common grid G are open-ended, tubular grids or electrodes G G and G respectively, with cathodes K K and K grids G and G and electrodes G G and G being maintained in the depicted, assembled positions thereof, by suitable, non-illustrated support means of an insulating material.

For operation of the electron gun A of FIG. 1, appropriate voltages are applied to the grids G and G and to the electrodes G G and G Thus, for example, a voltage of to minus 400V is applied to the grid G a voltage of 0 to 500V is applied to the grid G a voltage of 13 to ZOKV is applied to the electrodes G and G and a voltage of O to 400 V is applied to the electrode G with all of these voltages being based upon the cathode voltage as a reference. As a result, the voltage distributions between the respective electrodes and cathodes, and the respective lengths and diameters thereof, may be substantially identical with those of the unipotential-single beam type electron gun which is constituted by a single cathode and first and second, single-apertured grids.

With the applied voltage distribution as described hereinabove, an electron lens field will be established between grid G and the electrode G to form an auxiliary lens L as indicated in dashed lines, and an electron lens field will be established around the axis of electrode G by the electrodes G G and G to form a main lens'L again as indicated in dashed lines. In a typical use of electron gun A, bias voltages of 100V, 0V, 300V, ZOKV, 200V and 20V may be applied respectively to the cathodes K K and K the first and second grids G, and G and the electrodes G G, and G In the operation of so much of electron gun A as is described above, electrons emitted from the beam generating surfaces of cathodes K K and K are formed into paired electron beams B and B B and B' and B and B' passing through the paired apertures It and h',,,, I1 and /1, and It, and 12' of grid G. to be intensity modulated with what may be termed the red, green and blue" video signals applied between the respective cathodes and the first grid G It will be apparent that, with the arrangement of the apertures in grid G,, as described above and shown on FIGS. 1, 2 and 3, the beams B and B' emerge from grid G, in parallel, vertically spaced paths lying in a vertical plane that contains the axis of gun A, and the beams B and 8' and the beams B and B emerge from grid G in parallel vertically spaced paths lying in respective vertical planes that are symmetrically spaced from the vertical plane containing beams 8 and B' at opposite sides of the latter. Further, it will be seen that the beams B B and B and the beams B B and B',;, when emerging from grid G lie in respective horizontal planes that are disposed symmetrically above and below the horizontal plane containing the axis of gun A.

After passing through the respective apertures of the second grid G the several electron beams will traverse the electric field constituting the common auxiliary lens L, and be deflected thereby so as to cross each other substantially at the optical center of the main focusing lens L More specifically, as shown on FIGS. 1 and 3, the central beams B and B are converged in the vertical plane containing the axis of gun A, and the side beams B and B,, and side beams B and 8' are similarly converged vertically in their respective planes and simultaneously the latter planes are converged horizontally so that all of the beams will pass through main lens L and hence cross each other, substantially at the optical center of the main lens.

In emerging from main lens L the central beams 8,,- and B' will dimerge vertically from each other in a vertical plane containing the axis of gun A, and the side beams B and B,,, and B and B,; will diverge vertically from each other in respective vertical planes which diverge horizontally from the plane containing central beams B and 8' at opposite sides of the latter.

In order to insure that the paired beams B and B B and B' and B and 8' will have respective common landing spots on screen S, the electron gun A according to this invention further comprises vertical convergence deflecting means C, which, as shown on FIG. 5, acts on all of the veams after emergence of the latter from main lens L to upwardly deflect beams B 8 and B and to downwardly deflect beams B',;, 8' and B' As shown on FIGS. 1 and 3, the vertical convergence deflecting means C, may include a central plate P extending axially between electrode G and grid or grill A and lying in a horizontal plane containing the gun axis, and deflector plates O and Q which are spaced from plate P, above and below the latter to permit the passage of beams 8' 8' and B 6 between plates P, and Q and to permit the passage of beams B B and B between plates F,, and Q The deflector plates Q and Q35 have negative charges with respect to the central plate P, therebetween so that the resulting electric fields traversed by the beams will convergently deflect the beams B B and B and the beams 8' 8' and B,,.

More specifically, a voltage V," which is equal to the voltage applied to the electrode G may be applied to central plate P, and a voltage V which is some 200 to 300V lower than the voltage V is applied to the deflector plates QAS and Q85 to result in the application of a deflecting voltage difference or convergence deflecting voltages V between the plates P, and O and it is, of course, this convergence deflecting voltage V which will impart the requisite convergent deflection to the respective electron beams B 3 and B and 8' B and B',,.

In order to ensure that the vertical planes containing beams B and B',,, B and B' and B and B will intersect in a single vertical line lying in the plane of aperture grid or grill A the gun A according to this invention further comprises horizontal convergence deflecting means C which include vertical shielding plates P and P disposed in the depicted spaced, relationship at opposite sides of the gun axis between deflecting means C and grill A and axially extending, vertical deflector plates 0,, and Q which are disposed, as shown, in outwardly spaced, opposed relationship to shielding plates P and P respectively. Although depicted as substantially straight, it is to be understood that the deflector plates Q and Q may, alternatively, be somewhat curved or outwardly bowed, as is well known in the art.

The shielding plates P and P are equally charged and disposed so that the central electron beams B and B' will pass substantially undeflected between the shielding plates P and P while the deflector plates Q and Q have negative charges with respect to plates P and P,, so the respective electron beams B and B,,, And B and B R will be convergently deflected, as shown on FIG. 1, by the respective passages thereof between the plates P and Q and between the plates P and Q More specifically, the voltage V which is equal to that applied to electrode G and is applied to central plate P, of deflecting means C,,, may also be applied to shielding plates P and P while the voltage applied to deflector plates 0,, and O is some 200 to 300 V. lower than the voltage V to result in a convergence deflecting voltage between the plates P and Q and between the plates P and Q It is of course this convergence deflecting voltage which will impart the requisite horizontal deflections to beams B and B',, and to beams B and B B insuring that the vertical planes of such beams will intersect the vertical plane of central beams B G and B' at a common line in the plane of apertured grill A Preferably, the apertured grill A has its apertures in the form' of vertical extending slits. Thus, when the vertical line of intersection of the planes of beams B and B B and of beams B and B R with the plane of beams B and B' is centered in one of the slits of grill A the several beams pass through such slit. After passing through a slit of grill A the planes of beams B and B',, and beams B and B diverge from the plane of beams 8 and 8' as shown on FIG. 1, to strike or impinge on the respective color phosphors of a corresponding array thereof on screen S. Preferably, each set or array of color phosphors associated with a slit of grill A if composed of vertically extending red, green and blue phosphor stripes S S and S and, of course, such stripes are applied in a repetitive pattern across screen S.

As previously described and shown on FIGS. 3 and 5, by reason of the converging action of vertical deflecting means C the paired beams B and B B and B' and B and B B are converged to common landing spots on the respective phosphor stripes S 8 and S Thus, each phosphor stripe is excited or energized at a spot thereon to provide very intense or bright illumination at such spot without unduly increasing the beam current in any of the electron beams. Thus, the diameter of the landing spot of each pair of beams on the respective phosphor stripe can be kept desirably small to ensure that the resulting color picture will have good resolution. Of course, in producing such a color picture, all of the electron beams are made to simultaneously scan the face of screen S in a conventional manner, for example, by horizontal and vertical deflection yoke means (not shown) disposed around neck 12 and which receives horizontal and vertical sweep signals. Since, with the described arrangement, all of the electron beams are passed, for focussing through the center of the main lens L of electron gun A, the beam spots formed by impingement of the beams on color phosphor screen S will be substantially free from the effects of coma and/or astigmatism of said main lens, whereby color picture resolution of a high order will be provided. I

In the electron gun A described above with reference to FIGS. 1-5, each of the phosphor stripes S 8 and S is excited or merged by a pair of respective electron beams having a common landing sport on the corresponding stripe. However, in accordance with this invention, a color picture tube may be provided with a single electron gun which generates more than two beams for each color phosphor, with all of the beams corresponding to each color being converged to a common landing spot on the screen. For example, as shown of FIGS. 6-8, an electron gun A according to this invention may provide trios of electron beams B B' and B",,, B B' and B" and B B' and B,, for energizing the phosphor stripes S S and S respectively, with the beams of each trio being converged to a common landing spot on the respective phosphor stripe.

The gun A is generally similar to the previously described gun A, and differs therefrom in respect to the arrangement of apertures in grids G, and G and the construction of the vertical convergence deflection means C' More specifically, grid G, of gun A is seen to have trios of apertures h h' and h",,,, h h' and h and h [1' and h,,, arranged along laterally spaced apart vertical lines which are in alignment with the beam generating surfaces of cathodes K K and K respectively. Further, the apertures h h' and h are arranged along a horizontal line extending through the axis of gun A, and the apertures h h and h and the apertures h h", and h",,, are arranged along respective horizontal lines which are disposed above and below, respectively, the gun axis and symmetrically spaced from the latter. Similarly, the grid G of gun A has trios of apertures '12", hg and h hag, h gg and h gs, and hug, h gg and h" which are in axial alignment with the similarly identified apertures in grid G With the arrangement of the apertures in grids G, and G as described above with reference to FIGS. 6-8, the several beams, upon emerging from the apertures in grid G traverse the electric field constituting the auxiliary lens L and, with the exception of the beam B' are deflected thereby is that all of the beams will cross each other substantially at the optical center of the main focusing lens L More specifically, the beam B' lying in the axis of gun A is not deflected in passing through lens L whereas the other central beams B and 8",; are converged in the vertical plane containing the axis of gun A. The side beams B and 8",, and the side beams B and 8",, are similarly deflected vertically in their respective vertical planes to converge with the beams B',, and B,,, respectively. Simultaneously, the trio of beams B B R and B" and the trio of beams B B' and B",, are deflected horizontally in passing through lens L, to converge with the plane of central beams B 8' and B,;, so that all of the beams will cross each other substantially at the optical center of main lens L In emerging from main lens L,,, the central beam B',; will lie along the axis of gun A and central beams 8 and 8",; will diverge vertically therefrom in avertical plane containing the axis. Further, in emerging from main lens L,,, the side beams B B',, and B",, and the side beams B,,, B, and B",, will diverge from each other in respective vertical planes which diverge horizontally from the vertical plane containing beams 13, B' and B",;, with the side beams B',, and B',, lying in a horizontal plane that contains beam B',;.

In order to ensure that the groups of beams B,,, B R and B",,, B B' and B and B 8', and B, will have respective common landing spots on screen S, the gun A further comprises vertical convergence deflecting means C S which replaces the vertical convergence deflecting means C of FIGS. 1 and 3. The convergence deflecting means C S of gun A may be generally similar to the previously described horizontal convergence deflecting means C of gun A, but is arranged with its shielding plates P and P and its deflecting plates O and Q lying in respective horizontal planes. As in the case of deflecting means C, shielding plates P and P are equally charged so that beams 8' 8' and B',, passing therebetween are not deflected, while deflector plates 0,, and Q have negative charges with respect to plates P and P for example, 200 to 300 V. less than the latter, to provide electric fields between plates P and O and between plates P and Q85 by which beams B",,, 8",; and 3",, and beams B,,, B and 8,, are deflected downwardly and upwardly, respectively. The extent of such deflection is sufficient to converge beams B and B",, to a common landing spot with beam B on screen S, and similarly to converge beams B and 8",; with beam B' and beams B and 13",, with beams B to common landing spots on the screen.

In order to ensure that the vertical planes containing beams B 8' and B",,, beams B 3' and B" and beams B,,, B, B" B will intersect in a single vertical line lying in the plane of apertured grill A the gun A further comprises horizontal convergence deflecting means C which may be the same as the deflecting means C of FIGS. 1 and 3. Thus, the central beams B 8' and 8",; are substantially undeflected in passing between the shielding plates 1, and P which are at the same potential. However, beams B,,, B',, and B",, and beams B B',, and 8",, in passing between plates P and Q, and between plates P and Q, respectively, are horizontally deflected, as shown on FIG. 6, to converge with the vertical plane of the central beams B B and B" and intersect such plane at a vertical slit in grill A It will be apparent that, with the gun A three beams inpinge at a common landing spot on each color phosphor of screen S, whereby extreme picture brightness is attained without unduly increasing the current density in any of the beams. Although the horizontal convergence deflecting means C described above in connection with FIGS. 1 and 3 and FIGS. 6 and 7 is of the electrostatic type, it is to be understood that each such deflecting means C of the electrostatic type may be replaced by one of a magnetic type, for example, as illustrated in FIG. 9. The deflecting means C of the magnetic type is shown to include a magnetic shield member 14 which may be in the form of a tube of rectangular cross-section arranged axially after the vertical convergence deflecting means C or C' so as to permit the passage therethrough of the central beams B and B (as shown) or the central beams B 8' and B Extending from adjacent one side 14a of shield member 14 are two magnetic plates 15a and 15b which are in opposing, spaced relation to each other so as to permit the passage therebetween of beams B and B or beams B B and B", and a similar pair of magnetic plates 16a and 16b extend from the other side 14b of shield member 14 to permit the passage therebetween of beams B and B, or beams B,,, B, and B",,. The outer edge portions of plates 15a and 15b are bent away from each other to form magnetic poles 17a and 17b extending along the inner wall surface of the tube neck 12, and the outer edge portions of plates 16a and 16b are similarly bent to form poles 18a and 18b extending along the inner surface of neck 12. Provided at the outside of tube neck 12 are electromagnets 19a and 19b respectively including windings 20a and 20b on cores 21a and 21b which have pole portions in opposing relationship to the poles 17a and 17b and the poles 18a and 18b, respectively.

With the above described arrangement, the beams B and B' are not horizontally deflected since they are shielded by member 14 from the external magnetic field established by convergence current flows in windings 20a and 20b. However, beams B and B',, and beams B and B',; are horizontally deflected toward beams B and B' by reason of the magnetic flux distributions between plates 15a and 15b and plates 16a and 16b, respectively.

Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention.

What is claimed is:

1. A cathode ray tube comprising an electron receiving screen having sets of different color phosphors arranged in a repetitive pattern and each including a central color phosphor and two other color phosphors at opposite sides of said central color phosphor considered in one direction parallel to the plane of said screen; beam selecting means spaced from said screen and having apertures each corresponding to a respective one of said sets of color phosphors; and electron gun means including cathode means emitting electrons, first and second grid means arranged successively in adjacent opposing relation to said cathode means and having aligned apertures for passing electrons from said cathode means in respective electron beams directed toward said screen, each of said first and second grid means having a central group of apertures to define a central beam group for impingement on said central color phosphor of said color phosphor sets and two side groups of apertures spaced symmetrically in said one direction from said central aperture group at opposite sides of the latter to define respective side beam groups for impingement on said other color phosphors at respective sides of said central phosphor of each of said sets, the apertures in each of said central and side groups of apertures being spaced from each other in another direction substantially at right angles to said one direction, electron focusing lens means interposed between said grid means and said beam selecting means for focusing all of said beams of said groups at said screen, said focusing lens means having an optical axis and said aperture of said central group lying on a line that extends through said optical axis, and beam deflecting means located between said focusing lens means and said beam selecting means and including two sections arranged in axial succession, one of said sections deflecting beams of each of said groups in said other direction for converging all of the beams in each group to a respective common landing spot on said screen, and the other of said sections deflecting only said side beam groups in said one direction for converging the side beam groups with said central beam group at a common area of said beam selecting means so that, when said common area corresponds to an aperture of said beam selecting means, said common landing spots of the central and side beam groups will correspond to said central color phosphor and the other color phosphors of the respective color phosphor set.

2. A cathode ray tube according to claim 1, in which said apertures in said first and second grid means have spacings from each other in said second grid means that are equal to the spacings therebetween in said first grid means so that said beams are directed parallel to each other by the respective apertures of said grid means, said focusing lens means has an optical center on said optical axis, and an auxiliary lens means is interposed between said grid means and said focusing lens means for deflecting those electron beams which are spaced from said optical axis in passing through said apertures of the grid means so that all of said beams intersect substantially at said optical center of the focusing lens means.

3. A cathode ray tube according to claim 2, in which each of said groups of apertures consists of two apertures to provide two beams in each of said groups thereof.

4. A cathode ray tube according to claim 2, in which each of said groups of apertures consists of three apertures spaced apart equally in said other direction to said side ou s of beams, said deflectin lates bei at an ele iric l potential different from Fhat of said shielding plates to electrostatically deflect each of said side groups of beams in the direction toward said central group of beams.

6. A cathode ray tube according to claim 2, in which said other section of the beam deflecting means includes a tubular magnetic shield arranged along said optical axis for the passage therethrough of said central beam group, pairs of spaced magnetic plates extending outwardly from opposed sides of said shield for the passage between each of said pairs of magnetic plates of a respective one of said side beams groups, and magnet means operatively associated with said pairs of magnetic plates to establish, between each pair of plates, a magnetic field for deflecting the respective side beam group toward said central beam group.

7. A cathode ray tube according to claim 2, in which there are two beams in each of said-beam groups, and

said one section of the beam deflecting means includes a central plate extending in said one direction through said optical axis, and deflecting plates spaced in said other direction from said central plate for the passage therebetween of a respective beam from each of said groups, said deflecting plates being at an electrical potential different from that of said central plate to electrostatically deflect the two beams in each group toward each other.

8. A cathode ray tube according to claim 2, in which there are three beams in each of said groups with one of said three beams lying in a plane that extends in said one direction through said optical axis and the other two of said three beams lying in planes that are oppositely spaced in said other direction from said plane of the central beam, and said one section of the beam deflecting means includes a pair of shielding plates at equal electrical potential disposed in planes extending in said one direction and oppositely spaced in said other direction from said optical axis for the passage between said shielding plates of said central beam of each group, and deflecting plates spaced from said shielding plates for the passage therebetween of said other two beams of each group, said deflecting plates being at an electrical potential different from that of said shielding plates to electrostatically deflect each of said other two beams of each group toward the central beam of the respective group. 

1. A cathode ray tube comprising an electron receiving screen having sets of different color phosphors arranged in a repetitive pattern and each including a central color phosphor and two other color phosphors at opposite sides of said central color phosphor considered in one direction parallel to the plane of said screen; beam selecting means spaced from said screen and having apertures each corresponding to a respective one of said sets of color phosphors; and electron gun means including cathode means emitting electrons, first and second grid means arranged successively in adjacent opposing relation to said cathode means and having aligned apertures for passing electrons from said cathode means in respective electron beams directed toward said screen, each of said first and second grid means having a central group of apertures to define a central beam group for impingement on said central color phosphor of said color phosphor sets and two side groups of apertures spaced symmetrically in said one direction from said central aperture group at opposite sides of the latter to define respective side beam groups for impingement on said other color phosphors at respective sides of said central phosphor of each of said sets, the apertures in each of said central and side groups of apertures being spaced from each other in another direction substantially at right angles to said one direction, electron focusing lens means interposed between said grid means and said beam selecting means for focusing all of said beams of said groups at said screen, said focusing lens means having an optical axis and said aperture of said central group lying on a line that extends through said optical axis, and beam deflecting means located between said focusing lens means and said beam selecting means and including two sections arranged in axial succession, one of said sections deflecting beams of each of said groups in said other direction for converging all of the beams in each group to a respective common landing spot on said screen, and the other of said sections deflecting only said side beam groups in said one direction for converging the side beam groups with said central beam group at a common area of said beam selecting means so that, when said common area corresponds to an aperture of said beam selecting means, said common landing spots of the central and side beam groups will correspond to said central color phosphor and the other color phosphors of the respective color phosphor set.
 2. A cathode ray tube according to claim 1, in which said apertures in said first and second grid means have spacings from each other in said second grid means that are equal to the spacings therebetween in said first grid means so that said beams are directed parallel to each other by the respective apertures of said grid means, said focusing lens means has an optical center on said optical axis, and an auxiliary lens means is interposed between said grid means and said focusing lens means for deflecting those electron beams which are spaced from said optical axis in passing through said apertures of the grid means so that all of said beams intersect substantially at said optical center of the focusing lens means.
 3. A cathode ray tube according to claim 2, in which each of said groups of apertures consists of two apertures to provide two beams in each of said groups thereof.
 4. A cathode ray tube according to claim 2, in which each of said groups of apertures consists of three apertures spaced apart equally in said othEr direction to provide three of said beams in each of said groups.
 5. A cathode ray tube according to claim 2, in which said other section of the beam deflecting means includes a pair of shielding plates at equal electrical potential disposed at opposite sides of said optical axis for the passage therebetween of said central beam group, and deflecting plates spaced outwardly from said shielding plates for the passage therebetween of said side groups of beams, said deflecting plates being at an electrical potential different from that of said shielding plates to electrostatically deflect each of said side groups of beams in the direction toward said central group of beams.
 6. A cathode ray tube according to claim 2, in which said other section of the beam deflecting means includes a tubular magnetic shield arranged along said optical axis for the passage therethrough of said central beam group, pairs of spaced magnetic plates extending outwardly from opposed sides of said shield for the passage between each of said pairs of magnetic plates of a respective one of said side beams groups, and magnet means operatively associated with said pairs of magnetic plates to establish, between each pair of plates, a magnetic field for deflecting the respective side beam group toward said central beam group.
 7. A cathode ray tube according to claim 2, in which there are two beams in each of said beam groups, and said one section of the beam deflecting means includes a central plate extending in said one direction through said optical axis, and deflecting plates spaced in said other direction from said central plate for the passage therebetween of a respective beam from each of said groups, said deflecting plates being at an electrical potential different from that of said central plate to electrostatically deflect the two beams in each group toward each other.
 8. A cathode ray tube according to claim 2, in which there are three beams in each of said groups with one of said three beams lying in a plane that extends in said one direction through said optical axis and the other two of said three beams lying in planes that are oppositely spaced in said other direction from said plane of the central beam, and said one section of the beam deflecting means includes a pair of shielding plates at equal electrical potential disposed in planes extending in said one direction and oppositely spaced in said other direction from said optical axis for the passage between said shielding plates of said central beam of each group, and deflecting plates spaced from said shielding plates for the passage therebetween of said other two beams of each group, said deflecting plates being at an electrical potential different from that of said shielding plates to electrostatically deflect each of said other two beams of each group toward the central beam of the respective group. 